Polymers, by definition, are long chain molecules in which the atoms are bound to one another by means of strong covalent bonds. Hence one would expect exceptionally high strength and stiffness values in the chain direction since the applied load would then be opposed by the covalent bond themselves. On the contrary, most of the commercial polymers exhibit strength and stiffness values far below their theoretical limits. It is established that the modulus values of most of the commercial polymers are at least an order of magnitude less than their theoretical limits, thus severely limiting their use in many structural or load bearing applications. Therefore, the key to improved engineering properties lies in the preparation of highly chain extended/oriented polymers. As engineering materials polymers offer several advantages over metals and ceramics, in terms of high strength to weight ratio, cost efficiency, easy processability and improved corrosion resistance in many applications. See Table 1.
The need for oriented polymers has led to the development of several orientation techniques such as: solid state deformation of polymers, preparation of polymers with rigid chemical structures; and crystallization/fiber spinning from gels and dilute solutions. Much of the research in oriented polymers during the past two decades have been devoted towards an improvement and understanding of processing-morphology-property relations in uniaxially oriented systems. However, in the present invention, we are concerned with preparation of highly doubly oriented polymers from commercial plastics.